Aluminum Nitride Oxidation by Simultaneous TG and DTA

Abstract

This work is a study, by simultaneous thermogravimetry (TG) and differential thermal analysis (DTA), of the oxidation of a water resistant aluminum nitride powder which has a special protective coating, and an uncoated AlN powder which has become partially hydrated during its use. The activation energy for oxidation is estimated by the Kissinger and isoconversional methods. In the former method, the temperatures of the oxidation peaks were obtained from DTA and DTG curves. The activation energies for oxidation of the water resistant AlN, obtained by the Kissinger method, are 357±10 kJ mol^–1, 392±12 kJ mol^–1 using respectively DTG and DTA data. For the uncoated AlN, the values are 243±7 and 257±8 kJ mol^–1, respectively. By the isoconversional method, the average values obtained for coated and uncoated samples are, respectively, 323±10 and 224±7 kJ mol^–1. Therefore, the special coating, which protects the aluminum nitride from humidity action, also provides a higher resistance to oxidation.